1. Field of the Invention
The present invention relates to RF mixers. More particularly, it relates to a more linearized RF mixer utilizing frequency and bias compensation for improved performance.
2. The Prior Art
Presently, a standard Gilbert cell is used for mixer designs in RF circuits. A gilbert cell generally consists of a single or double differential pair of transistors in the lower tree of the mixer. Under low voltage conditions, second order effects such as the IF output riding on the large local oscillator feed-through, will cause clipping of the IF signal and result in intermodulation products. In addition, small V.sub.BE changes caused by temperature or second order bias dependencies will cause current and gain variations that limit the performance of the circuit. It is therefore desireable to have an RF mixer that operates independent of temperature changes and variations in the V.sub.CC level.